The present disclosure relates generally to an imaging module and an imaging reader for, and a method of, reading a target, such as a bar code symbol, to be electro-optically read by image capture over a field of view through a window that is positioned in direct, sealed contact with the module, and, more particularly, to preventing light from aiming and/or illuminating and/or indicating and/or object sensing systems onboard the module from interfering with a successful reading of the target.
Solid-state imaging readers have long been used, in both handheld and hands-free modes of operation, in many industries, such as retail, manufacturing, warehousing, distribution, postal, transportation, logistics, etc., to electro-optically read targets, such as one- or two-dimensional bar code symbols to be decoded. A known imaging reader generally includes a housing having a window, and an imaging module, also known as a scan engine, mounted in the hosing at a spacing from the window. The module has a chassis with a plurality of interior compartments. An aiming light system, which has an aiming light source contained in one of the compartments, directs one or more visible aiming lights through the window to a target to visually locate the target and, thus, advise an operator which way the reader is to be pointed in order to position the aiming lights on the target, prior to reading. An illuminating system, which has an illuminating light source contained in another of the compartments, emits one or more illuminating lights through the window toward the target to illuminate the target, especially in dimly lit environments. An imaging system, which has a solid-state imager contained in still another of the compartments, captures an image of the target through the window over a field of view. An indicating system, which has an indicating light source supported on the chassis, emits an indicating light that visually indicates when the target has been successfully read. An object sensing system, which has a wakeup light source supported on the chassis, emits an object sensing light at the target to detect the entry of the target into the field of view. These systems are generally located in close proximity with one another on the chassis, especially when a small-sized chassis is desired for a particular reader.
Although generally satisfactory for their intended purpose, the close mutual proximity of these systems could cause the aiming and/or illuminating and/or indicating and/or object sensing lights to stray and leak into the compartment containing the imager, and such cross-talk could interfere with a successful imaging and reading of the target. This leakage is exacerbated by the spaced-apart window, which could rearwardly reflect, for example, the aiming and/or illuminating lights back to the imaging system in the chassis. In addition, the aiming and/or illuminating and/or object sensing lights could stray and leak to the indicating system and erroneously indicate that a target has been successfully read. Furthermore, dust, moisture, dirt, and like contaminants could migrate not only among the systems and interfere with their performance, but also could be deposited on the spaced-apart window. Reflections of the aiming and/or illuminating and/or object sensing lights from such contaminants on the window could create bright spots in the captured image and further degrade reading performance.
Accordingly, it would be desirable to environmentally seal, optically isolate, and resist entry of stray aiming and/or illuminating and/or indicating and/or object sensing light into, the compartment containing the imager, to mitigate stray internal reflections, and to improve overall reading performance.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and locations of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The imaging module, the imaging reader, and the method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.